This invention generally relates to the erasure of information from magnetic storage media systems, both analog and digital types and, more particularly, to magnetic media erasure systems for achieving sufficiently deep AC and/or DC erase to facilitate declassification of U.S. Government classified magnetic media of the high coercivity type.
It is known that DC erasure is necessary prior to AC degaussing to successfully erase National Security Agency Class II or higher coercivity magnetic media. AC degaussing alone will not suffice. Further, it is known that erasure in as many spatial planes as possible (normal, transverse and longitudinal) facilitates erasure of the primary signal and its harmonics to optimum depths. However, existing NSA Class I AC Degausser systems have proven unsatisfactory on high coercivity media, on the order of 750 Oersteds or more, in achieving the minimum targeted bulk erase level of -90 dB below signal saturation that has been set for the declassification of classified magnetic media.